The invention relates to ostomy appliances for receiving bodily waste from colostomy or ileostomy patients and in particular to the filters used in connection with ostomy bags for removal of malodour of flatus collected in the bag, before the gases are released to the environment.
A number of publications describes such filters and the problem with solid or semi-liquid waste blocking the filter and causing malfunctioning of the filter. Methods for protecting such filters from liquid and solid bodily waste are also described. Such methods include covering the inlet opening of the filter with a porous protection film and with a foam.
Thus, EP 607 028 discloses an ostomy bag for holding body waste comprising a bag formed from a flexible plastic sheet material defining a waste collection chamber. The bag defines a gas outlet proximate a top end portion of the bag. A deodorizing filter is joined to the bag in alignment with the gas outlet means for deodorizing gaseous waste material before the gaseous waste exits from the bag through the gas outlet. In the bag, there is provided means for protecting the deodorizing filter from contact with semi-liquid waste material, and for permitting the flow of gaseous waste, and for obstructing the flow of semi-liquid waste, the protection means comprises a porous protection film preceding the deodorizing filter and further comprising an open cell foam material preceding the porous protection film so that the gaseous waste has to pass through the open cell foam material, and thereafter through the porous protection film before it passes through the filter. It is thereby sought to provide a multi stage filter system that prevents semi-liquid waste material from contaminating the deodorizing element.
U.S. Pat. No. 6,135,976 discloses an ostomy appliance comprising a front wall and a rear wall of a flexible material. One of the walls has one or more vents through which gas may escape from the bag. The patent discloses a filter covering the vent, which filter comprises an elongated substantially flat filter body of a porous filter material interposed between gas and liquid permeable walls which are sealed to the filter body along its longitudinal edges. Gas inlet and outlet openings are provided in communication with the filter material in adjacent ends of the longitudinal filter. The gas and liquid impermeable walls are sealed to the upper and lower surfaces of the filter body. In use, gas flows longitudinally through the filter from the inlet opening to the outlet opening. The inlet opening is covered with a micro porous hydrophobic and oleophobic membrane, and a foam material is placed so that it precedes said membrane but also covers the inlet opening of the vent.
These filters have improved resistance to wetting and blocking of the deodorizing filter. However, even if improved, it has been found that such filters may eventually become blocked due to faeces being deposited therein, which is inconvenient and unpleasant for the patient.
The filters according to the present invention comprises a protective element in the form of an open celled compressible material having a memory and having a very small pore size, suitably the pore size is above 60 PPI (pores per inch).
It has been found that by the use of the protective element according to the invention, the membrane or the porous or perforated film covering the inlet opening of the deodorizing filters described above has become superfluous.
Moreover, it has been found that filters having protective elements extending in the direction of the gas flow and having a very small pore size may be cleaned in situ.
The filters described in the above publications generally describe the use of protective foam elements covered by foils allowing access of gases through a few small openings in the foil which prevents solid or semi-liquid bodily waste from entering the protective foam element. Thus, once bodily waste get into these protective foams and block for the passage of gases, they are difficult to clean due to the limited access to the protective foam elements.
The filters according to the invention are characterised by having a relatively large opening in the channel or compartment containing the protective element, the relatively large opening enabling in situ cleaning of the protective element by squeezing solid or semi-liquid waste out and away from the protective element.
None of the above-mentioned publications describes or suggest in situ cleaning of the filters for ostomy appliances.